1. Field of the Invention
The invention proceeds from a composite material comprising a filler and a matrix which embeds the filler, in which material at least one physical quantity causes at least two nonlinear changes in a material property or at least one nonlinear change in each case in one of at least two material properties as a result of acting on the filler and/or the matrix.
2. Discussion of Background
EP 0 548 606 A2 discloses an electrical resistor. Said resistor contains a resistor body composed of a composite material containing a polymer as matrix. Embedded in the polymeric matrix as fillers are an electrically conductive powder, for instance soot, and a powdered varistor material, for instance based on a sprayed granular material. In this resistor, the electrically conductive powder forms current paths passing through the resistor body during normal operation. Above a certain value of the current, the resistor body heats up intensely. The polymer matrix expands considerably and thus separates the particles of the electrically conductive filler which form the current path. The current is interrupted. If the voltage across the resistor body or locally in the resistor body increases too strongly under these circumstances, the particles of the varistor material form percolating paths, which dissipate the undesirably high voltage, locally or throughout the entire resistor body above a specified limit value of the voltage. However, two different fillers are needed for the abovedescribed functions of current interruption and of voltage limitation, which functions are caused by a nonlinear behavior of the composite material with respect to the current carried or to the applied voltage. For some applications this is undesirable and may possibly result in difficulties in the production of the composite material.